This invention relates generally to the backup and recovery of computer databases, and more particularly to the backup and recovery of linked databases having different database structures in an integrated database system.
There are several client/server groupware software products which enable collaboration among users in workgroups on a network. These products may include several collaborative applications such as instant messaging, e-mail, calendar and browser applications, and may store data of workgroup users in one or more databases. Due to the generally unstructured nature of the data, the databases are typically loosely structured. An example of such a collaborative client/server software product is Lotus Notes/Domino, a product of IBM. The Lotus Notes/Domino product is a cross-platform, secure, distributed database application development environment that includes pre-built collaborative applications such as e-mail, calendar, etc. The product comprises a Domino server and a Notes client. Domino and Notes data is stored in databases referred to as either a Notes database or a Domino database. Notes databases are loosely structured. They are document centric, meaning they allow multiple values in items (fields). They do not have a schema, tables, keys, inter-relational integrity, or other characteristics of more structured types of databases, such as relational databases. The Notes/Domino database may be distributed, i.e., there may be several copies of the same database replicated on different servers and clients. Databases stored on a Notes client are referred to as local databases, are visible only to a local user, and can be accessed by only a single user at a time. The databases stored on the Domino server are visible to many users, and can be accessed simultaneously by multiple users. The schema-less, substantially unstructured database architecture means that the database is uniquely able to store the highly disparate data types which characterize a Notes/Domino environment.
Although the Notes/Domino database has a full text search engine, its lack of structure is a disadvantage because it is not amenable to the more powerful and flexible constructs and SQL (Structured Query Language) queries available in more structured databases, such as a relational database. As a result, it is desirable to link a loosely structured database, such as the Notes/Domino database, with a relational database to form an integrated database system by mapping data from the loosely structured database to the relational database. Accordingly, IBM now provides support for mapping Domino databases to its DB2 relational database product. Mapping of Domino data to the DB2 database results in data and information being stored in two separate databases. Thus, it is also necessary to record data about the mapping so that data may be recovered. The Domino server therefore creates a small operating system (O/S) file referred to as a stub file in its data directory located on the Domino host that provides a link to the DB2 database. Additionally, it records metadata in a catalog stored in the DB2 database that provides information on the mapping of the Domino stub file and the corresponding DB2 tablespace that contains the real data.
The importance of backing up mission-critical data in computer systems is well known. Although the reliability of computer equipment has improved greatly in recent years, system and hardware failures still occur, sometimes with catastrophic results. It is important, therefore, to back up computer systems to protect them from the loss of valuable data and to enable recovery of that data in the event of a failure. In a network environment, where users depend upon shared data and the amount of data grows continuously, the need to protect and manage data becomes even more critical. A viable backup strategy includes regular backups of databases, as well as backups of archive logs. Without archive logs, a database may only be recovered up to the time of its last full backup.
For integrated database systems, such as Domino-DB2 databases, it is also necessary to back up the metadata and mapping information in the catalog, so that in the event of a failure, the data as well as the catalog mapping information may be recovered and restored.
IBM provides guidance as to how to backup and recover Domino data stored in DB2. However, the steps are manual, require an in-depth knowledge of DB2 and Domino, and are error prone. Separate methods are used to independently backup and recover data stored in a traditional format in the Domino database and backup and recover data stored in the DB2 database. Moreover, after DB2 data has been recovered, it is necessary to ensure that the Domino server is aware of that recovered data by manually recreating the operating system (O/S) stub file, and by updating the DB2 catalog of metadata for the Domino data stored in DB2.
It is desirable to facilitate the backup and recovery of integrated databases, such as Domino and DB2 databases, by providing automated and programmatic approaches for backup and recovery that avoid the difficulties and errors associated with the current approaches. It is to these ends that the present invention is directed.